This invention relates to an improved method for extending the useful life of aqueous emulsions useful as metal-working lubricants/coolants. More particularly, this invention relates to an improved method for reclaiming aqueous emulsions which have become contaminated with solid metal particles, e.g., during use as metal-working lubricants/coolants.
It is customary and conventional to use a lubricant and/or coolant composition while working metal. Among the metal-working operations in which such compositions are normally used are cutting, grinding, drilling, drawing, ironing, boring, broaching, milling, metal shaping, bending and the like. Among the lubricant/coolant compositions used in these metal-working operations are aqueous emulsions, for example, emulsions comprising oil (including synthetically derived oil) and water.
During use, these emulsions often become contaminated with solid particles of the metal being worked. Such particles can become abrasive and actually interfere with the metal-working operation. For example, an emulsion used as a lubricant/coolant in an aluminum drawing operation e.g., to produce aluminum beverage cans becomes contaminated with aluminum particles which can cause defects in the aluminum article being produced. Filtering systems have been suggested to remove these metal particles. However, these systems have been largely ineffective, particularly when the metal particles are exceedingly small, e.g., about 0.5 to about 5.0 microns.
Another problem with such emulsions is that upon being recycled continuously over a period of time the emulsions are attacked by bacteria and other microbes which give the emulsion a very unpleasant odor.
Biocides have been employed in the past in an attempt to correct this problem. However, these biocidic materials add to the expense of the metal-working operation and, often require relatively sophisticated monitoring and control equipment to maintain the concentration desired.
Eventually, because of one or both of these problems, the emulsion is removed from service and is either discarded or reprocessed, using relatively complex and expensive techniques to reclaim, for example, the oil part of the emulsion.
Therefore, one object of the present invention is to provide an improved method for reclaiming an aqueous emulsion which has been contaminated with metal particles.
Another object of the present invention is to provide such a method and obtain an emulsion useful as a metal-working lubricant/coolant.
An additional object of the present invention is to provide an improved method of treating an aqueous emulsion to reduce the microbe activity in the emulsion.
A still further object of the present invention is to provide an improved method of metal-working. These and other objects of the present invention will become apparent hereinafter.